Propeller.



T. A MACDONALD,

PROPELLER.

APPLICATION FILED FEB.16, 1914.

M) W ATTORNEYS THE NORRIS PETERS 60.. PHoTc-LITHQ, WASHINGTON DV 5.

THOMAS a. raacnonnrin, on PATERSON, new annsnr.

rnor-nLLnn.

Application filed February 16, 1914.

To all whom it may concern:

Be it known that I, THOMAS A. MACDON- ALD, a subject of the King of England, and a resident of Paterson, in the county of Fassaic and State of New Jersey, have made certain new and useful Improvements in Propellers, of which the following is a specification.

My invention relates to improvements in propelling devices, especially those propellers which are designed for aeroplanes, and it consists in the combinations, construotions, and arrangements herein described and claimed.

An object of my invention is to provide a propeller which not only exerts a driving force in the direction of flight, but also exerts a lifting force, this lifting force being due to the peculiar shape of the blade of the propeller.

A further object of my invention is to provide a device of the type described in which a substantially semicircular shield is used on one side of the propeller shaft, through which the blades of the propeller revolve in such a manner that a maximum lifting effect is obtained.

Other objects and advantages will appear in the following specification and the novel features of the device will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings forming part of this application in which Figure 1 is a face view of the propeller, the shield being shown in section, Fig. 2 is a sectional view along the line 22 of Fig. 1, Fig. 8 is a sectional view along the line 3-3 of Fig. 1, Fig. 4 is a sectional view along the line 4-"4 of Fig. 3, Fig. 5 is a sectional View along the line 55 of Fig. 1.

Referring now particularly to Fig. 1, it will be seen that the shaft a; is provided with hubs 8 to which blades 9 are secured. As will be seen from the drawings these blades are widest at their outer ends and taper as they approach the hub to which they are secured. In Fig. 3, it will be seen that each of the blades is curved from its outermost edge 9 to the inner edge 9". The blades are not only curved in the direction of their length but are also curved in a direction at right angles thereto, as shown in Fig. a. Beginning at a point 9 near the rear edge of each blade and extending to the outer edge 9 of the blade are a series of Specification of Letters Patent.

Patented Apr. is, rails.

Serial No. 818,9t3.

slots 9, which are inclined away from the hub 8. It will be understood that the rear edge, as referred to in the specification and in the appended claims, is that edge which is to the rear when the direction of movement of the blade in the normal operation of the machine is considered. lhis provides a series of segments 9 which are formed integrally with the blade. The segments are fluted for a purpose hereinafter set forth and the edges of the adjacent segments are slightly overlapped, as shown in dotted lines in Fig. 3. Furthermore these segments are twisted or bent so that there will be a space between the adjacent edges of the segments through which the air can escape.

Arranged to cooperate with each of the propellers is a substantially semicircular shield like that shown in Figs. 1 and 2. This shield consists of an arc-shaped back 10, which is concentric with the axis of the shaft, and divergent sides 11 and 12. The shield is suitably supported by the members l3 secured to the frame portion 3.

From the foregoing description of the various parts of the'device the operation thereof may be readily understood.

With the propellers arranged, as stated, a forward thrust is given to the machine in the manner of the ordinary propeller, but in addition tothat there is also a lifting effect due partly to the curvature of the blades and partly to the fluted segments 9*. It will be apparent that as the blades revolve the air will be condensed in front of the blades and underneath the curved portion thereof in such a manner that the resultant of the thrust of the propeller is not merely parallel to the axis of the propeller, but is directed downwardly. This gives an upward lift to the propeller, and hence tends to lift the machine upwardly. As the blades revolve the air is caught underneath the fluted segment and tends to escape through the slots 9 between these segments. 1he frictional re sistance of the air in passing through these segments enables the segments to get a grip on the air for lifting the device that they would not otherwise have. The device will work even if the segments are not fluted, but by flirting the segments a greater area is attained in a given length of the propeller blade and in view of the fact that there will be greater frictional surface to present to the air, the lifting effect of the air in passing these segments will therefore be augmented.

I equal to the downward thrust on the other,

and hence there would be no lifting movement, but with one side of the propeller inclosed in a shield the upward thrust which would tend to drive the device downwardly is to a large extent eliminated. In order to attain the highest efficiency I construct the shield as shown in Fig. 2. with divergent sides. This permits the air to have freedom of movement toward the upper end of'the shield, while in the lower .side the moving air creates a vacuum which tends to draw the blade in with it. lhe widening of the shield atthe top thus reduces the air friction and augments the lifting effect, as stated.

It will also be apparent that the use in an aeroplane of propellers made as described herein will materially reduce the area of the main: sustaining planes, while at the same I time giving the necessary lifting effect.

This is due to the fact, as stated above, that .the propellers exert a considerable lifting efiect. as well as a'propelling effect in the line of flight.

I claim: 7 1. In a propellingdevice for aeroplanes, a shaft, a plurality of curved blades rigidly secured to said shaft, and a series of integral segments carried by each of said blades on the rear edge thereof, the adjacent edges of the segments overlapping one another, and the overlapping edges being spaced apart to permit the passage of air.

2. In a propelling device for aeroplanes, a shaft, a plurality of blades rigidly secured to said shaft, each of said blades being curved in the direction of its length and also being curved in a direction at right angles thereto, and a series of integral segments carried by each of said blades on the rear edge thereof, the adjacent edges of the segments overlapping one another.

3. In a propellin device for aeroplanes, a shaft, a plurality of blades rigidly secured to said shaft, each. of said blades being curved in the direction of its length and also being curved in a direction at right angles thereto, and a series of integral segments carried by each of said blades on the rear edge thereof, the adjacent edges of the segments overlapping one another and being spaced apart to permit the passage of air.

4. In a propelling device for aeroplanes, a shaft, a plurality of blades rigidly secured to said shaft, each of said blades being curved in the direction of its length and also being curved in a direction at right angles thereto, and a series of integral segments carried by each of said blades on the rear edge thereof, the adjacent edges of the segments overlapping one another and being spaced apart to permit the passage of air, each of said segments being fluted or corrugated in a directi on substantially parallel with the length of the blade.

THOMAS A. MACDONALD.

Witnesses L. A. STANLEY, SoLoN O. KnMoN.

Copies of this patent may he obtained for five cents each, by addressing the Commissioner) of Patents, Washington, D. 0. 

